This invention relates to plastic drums and drum assemblies, preformed plastic inserts for use in plastic drum assemblies, and methods of forming plastic drums and plastic drum assemblies.
Steel and fiber drums have long been utilized for the shipment and storage of liquid, paste, powder, and solid products. A fundamental requirement of all such drums is the need for safe and convenient handling. For this purpose, a number of specialized devices have been developed including fork-lift trucks which can grasp the drum around its center girth or by other means. One such means which is widely used is the "parrot's beak" mechanism; this device includes a pair of jaws which engage a structure on the steel lid and locking band of such drums. More recently, plastic drums blow molded from high density polyethylene have become popular. These drums have rounded corners at the ends, and such corners and the slick surface of the polyethylene plastic make the handling of these drums very difficult. It is not feasible to apply the "parrot's beak" jaws to the top rim of such a plastic drum due to the absence of a suitable structure to be engaged by the jaws of the "parrot's beak." This has led to a number of attempts to modify the plastic drum construction to accommodate the " parrot's beak" jaws. A number of these prior art expedients will be discussed more fully hereinafter with reference to the drawings. It will be noted here, however, that the most promising of the prior art expedients involves the provision of a preformed plastic insert fused to the corner of the drum with the insert surmounted on the normal drum structure. This is accomplished by altering the conventional mold cavity used for blow molding the plastic drum; a groove is cut through the corner of the mold cavity wall for holding the preformed plastic insert. However, this procedure unduly complicates the design, construction and operation of the metal mold.